Separator for metal air cells

ABSTRACT

An alkaline electrochemical cell includes a cathode; a gelled anode having an anode active material and an electrolyte; and a separator disposed between the cathode and the anode; wherein the separator includes a non-conductive, porous material having a mean pore size of about 1 micron to about 5 microns, a maximum pore size of about 19 microns, and an air permeability of about 0.5 cc/cm2/s to about 3.8 cc/cm2/s at 125 Pa.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/559,385, filed on Sep. 15, 2017, the content of whichis incorporated herein by reference in its entirety for any and allpurposes.

FIELD

The present technology is generally related to the field ofelectrochemical cells. In particular, the technology is related toseparators for electrochemical cells, the separators exhibiting improvedpore size and air permeability.

SUMMARY

In one aspect, an alkaline electrochemical cell separator is providedwhich includes a non-conductive, porous material, wherein the separatorhas a mean pore size of about 1 micron to about 6 microns, and an airpermeability of about 0.5 cc/cm²/s to about 3.8 cc/cm²/s at 125 Pa.

In another aspect, an alkaline electrochemical cell is provided whichincludes a cathode; a gelled anode comprising an anode active materialand an electrolyte; and a separator disposed between the cathode and theanode; wherein the separator comprises a non-conductive, porous materialhaving a maximum pore size of 1 about 19 microns, and an airpermeability of about 0.5 cc/cm²/s to about 3.8 cc/cm²/s at 125 Pa.

In various embodiments that are combinable with the above aspects andembodiments, the non-conductive, porous material comprises anion-permeable, non-woven sheet (barrier). In some embodiments that arecombinable with the above aspects and embodiments, the separator has anair permeability of from about 500 cc/cm²/min to about 3000 cc/cm²/min,at 1 KPa. In some embodiments that are combinable with the above aspectsand embodiments, the separator has a mean pore size of about 0.5 micronto about 3.8 microns. In some embodiments that are combinable with theabove aspects and embodiments, the separator has a basis weight of about20 g/m² to about 32 g/m². In some embodiments that are combinable withthe above aspects and embodiments, the separator has a dry thickness offrom about 60 microns to about 120 microns. In some embodiments that arecombinable with the above aspects and embodiments, the separator ispermeable to hydroxide ions and water. In some embodiments that arecombinable with the above aspects and embodiments, the separator has asingle layer of non-conductive, porous material wound twice.

In various embodiments that are combinable with the above aspects andembodiments for the electrochemical cell, about 10% to about 60% byweight of the anode active material relative to the total amount ofanode active material has a particle size of less than about 75 microns,about 5% to about 30% by weight relative of the total zinc alloy has aparticle size of greater than about 150 micrometers, and less than about10% by weight of the anode active material relative to the total amountof anode active material has a particle size of less than about 45microns. In some embodiments that are combinable with the above aspectsand embodiments, the anode active material has an apparent density fromabout 2.40 g/cc to about 3.40 g/cc. In some embodiments that arecombinable with the above aspects and embodiments, the electrolyte has ahydroxide concentration of about 24 wt % to about 36 wt %. In someembodiments that are combinable with the above aspects and embodiments,the anode active material includes a zinc alloy. In some embodimentsthat are combinable with the above aspects and embodiments, the zincalloy includes zinc, indium, and/or bismuth, and/or lead. In otherembodiments, the zinc alloy includes about 100 ppm to about 300 ppm ofbismuth, and/or about 100 ppm to about 300 ppm of indium, and/or about50 to 500 ppm of lead. In some embodiments that are combinable with theabove aspects and embodiments, the anode includes from about 62% toabout 72% by weight of the zinc alloy, relative to the total weight ofthe anode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an interaction plot for no-delay ANSI performance fora LR6 cell including a separator in accordance with the presentdisclosure.

FIG. 2 is a graph illustrating grooming performance for a LR6 cellincluding a separator in accordance with the present disclosure.

FIG. 3 is a graph illustrating high temperature performance of toy testafter 1-week storage at 160° F., and of game test after 2-weeks ofstorage at 130° F., for a LR6 cell including a separator in accordancewith the present disclosure.

FIG. 4 is a graph illustrating LR6 cell high temperature performance ofDSC tests after 2-weeks of storage at 130° F.

FIG. 5 illustrates an interaction plot for no-delay ANSI performancecomparison of LR6 cells including a separator in accordance with thepresent disclosure.

FIG. 6 is a graph illustrating the DSC performance of LR6 cellsincluding a separator in accordance with the present disclosure.

FIG. 7 is a graph illustrating the grooming performance for LR6 cellsand whose performance is illustrated in FIG. 5 and FIG. 6.

FIG. 8 is a graph illustrating the high temperature storage performancefor LR6 cells and whose performance is illustrated in FIG. 5 and FIG. 6.

It is to be further noted that the design or configuration of thecomponents presented in these figures are not scale, and/or are intendedfor purposes of illustration only. Accordingly, the design orconfiguration of the components may be other than herein describedwithout departing from the intended scope of the present disclosure.These figures should therefore not be viewed in a limiting sense.

DETAILED DESCRIPTION

Various embodiments are described hereinafter. It should be noted thatthe specific embodiments are not intended as an exhaustive descriptionor as a limitation to the broader aspects discussed herein. One aspectdescribed in conjunction with a particular embodiment is not necessarilylimited to that embodiment and may be practiced with any otherembodiment(s).

As used herein, “about” will be understood by persons of ordinary skillin the art and will vary to some extent depending upon the context inwhich it is used. If there are uses of the term which are not clear topersons of ordinary skill in the art, given the context in which it isused, “about” will mean up to plus or minus 10% of the particular term.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the elements (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Recitation of ranges of values herein are merely intended toserve as a shorthand method of referring individually to each separatevalue falling within the range, unless otherwise indicated herein, andeach separate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein may beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the embodiments and does not pose alimitation on the scope of the claims unless otherwise stated. Nolanguage in the specification should be construed as indicating anynon-claimed element as essential.

Ratio, concentrations, amounts, and other numerical data may bepresented herein in a range format. It is to be understood that suchrange format is used merely for convenience and brevity and should beinterpreted flexibly to include not only the numerical values explicitlyrecited as the limits of the range, but also to include all theindividual numerical values or sub-ranges encompassed within that rangeas if each numerical value and sub-range is explicitly recited. Forexample, 5 to 40 mole % should be interpreted to include not only theexplicitly recited limits of 5 to 40 mole %, but also to includesub-ranges, such as 10 mole % to 30 mole %, 7 mole % to 25 mole %, andso forth, as well as individual amounts, including fractional amounts,within the specified ranges, such as 15.5 mole %, 29.1 mole %, and 12.9mole %, for example.

As used herein, the term “zinc anode” refers to an anode that includeszinc as an anode active material.

As used herein, “fines” are particles passing through a standard 200mesh screen in a normal sieving operation (i.e., with the sieve shakenby hand). “Dust” consists of particles passing through a standard 325mesh screen in a normal sieving operation. “Coarse” consists ofparticles not passing through a standard 100 mesh screen in a normalsieving operation. Mesh sizes and corresponding particle sizes asdescribed here apply to a standard test method for sieve analysis ofmetal powders which is described in ASTM B214. Typically, fines compriseparticles smaller than 75 microns, coarse comprises particles greaterthan 150 microns, and dust comprises particles smaller than 45 microns.

As used herein, “aspect ratio” refers to the dimension determined by theratio between the length of the longest dimension of the particle andthe relative width of the particle.

As used herein, the term “ppm” means parts per million by weight, unlessexplicitly expressed otherwise.

As used herein, the term “air permeability” denotes the volume of airallowed to flow per an area of the separator.

The present disclosure is directed to improving the performance ofcells, such as alkaline cells. The disclosure is also direct towardsuppressing undesirable reactions at the separator-electrode interfacethat can lead to anode to cathode electrical shorting.

Alkaline electrochemical cells are equipped with a separator tophysically separate the anode and cathode and prevent any electroniccurrent passing through them. Additionally, the separator functions topermit the passage of ionic current with minimum hindrance and keep thezinc surface properly wetted by the electrolyte. Ideally, the separatorshould have a uniform dry thickness and uniform pore size distribution.

Conventional alkaline cells typically employ a non-woven separator sheetas the separator. The sheet is typically wound, or wrapped, upon itselfto form a cylindrical shape that is then disposed between the anode andcathode electrode materials, the anode material being contained withinthe separator. Many times, the winding, or wrapping, is done multipletimes to ensure sufficient and efficient separation between theelectrodes (i.e. that there is sufficient overlap to ensure leakage andshorting between the anode and cathode is prevented). As anillustration, where the wrapping is done with three integral wraps, itmay be referred to as having a 1×3 separator wrapping arrangement, i.e.a single sheet rolled/wrapped upon itself in a roll fashion, threetimes. This arrangement typically results in a thick separator whichoccupies significant volume in the cell, thereby resulting in asubstantial decrease in the available volume needed for activeingredients, such as zinc anode particles. This is especially true forsmaller cells like LR06 or LR03 cells, where the outer dimensions of thecell are standardized and cannot be changed. It has now been found thatthe number of separator wraps in electrochemical cells may be reduced byproviding a separator with improved properties such as pore size and airpermeability.

In one aspect, an alkaline electrochemical cell is provided. The cellsmay include a cathode, an anode which includes an anode active materialand an electrolyte, and a separator disposed between the cathode and theanode. In another aspect, an alkaline electrochemical cell separatorincludes a porous material of desired pore size and air permeability toallow for a reduced number of separator wraps within the electrochemicalcell, as compared to convention cell constructions.

The separator may be made of any suitable alkaline resistant,ion-permeable, non-conductive, synthetic or natural, woven or non-wovenporous material, including, but not limited to, polymer materials,Tencel® (lyocell), mercerized wood pulp, polypropylene, polyethylene,cellophane, cellulose, methylcellulose, rayon, nylon and combinationsthereof. In some embodiments, the non-conductive, porous materialincludes an ion-permeable, non-woven sheet (barrier). In someembodiments, the separator is composed of a porous material whichincludes a paper composed of one or more polymeric fibers. The separatormay be made of a porous material which includes one or more polymericfibers with an effective amount of a surface active agent embeddedtherein. Suitable polymeric materials for the polymeric fibers include,but are not limited to, polyvinyl alcohol, polyamides, polyethyleneterephthalate, polypropylene terephthalate, polybutylene terephthalate,polyvinylidene fluoride, polyacrylonitrile, polypropylene, polyethylene,polyurethane and blends, mixtures and copolymers thereof. Illustrativepolymeric fibers may include, but are not limited to, materials such asrayon, nylon, and the like, and combinations of any two or more thereof.In some embodiments, the separator includes a non-woven material formedfrom alkaline resistant fibers. In some embodiments, the separatorincludes a non-woven paper. In some embodiments, the non-conductive,porous material includes polyvinyl alcohol and rayon fibers.

In various embodiments, the separator may have a maximum pore size equalto or less than about 25 microns. This includes a maximum pore size ofabout 24 microns, about 22 microns, about 18 microns, about 15 microns,about 10 microns or about 8 microns. In some embodiments, the separatorhas a maximum pore size of about 22 microns. In other embodiments, theseparator has a maximum pore size of about 19 microns. In someembodiments, the separator has a mean pore size, when measured with aPMI capillary flow porometer, of from about 0.01 micron to about 25microns, about 0.1 micron to about 20 microns, about 0.5 micron to about15 microns, about 1 micron to about 10 microns, about 2 microns to about8 microns, or about 3 microns to about 5 microns, and ranges between anytwo of these values or less than any one of these values. In someembodiments, the separator has a mean pore size, when measured with aPMI capillary flow porometer, of from about 1 micron to about 6 microns.In other embodiments, the separator has a mean pore size, when measuredwith a PMI capillary flow porometer, of from about 2 microns to about 5microns. In some embodiments, the separator has a maximum pore size offrom about 1 micron to about 6 microns. In other embodiments, theseparator has a mean pore size of from about 2 microns to about 5microns.

In various embodiments, the separator may have air permeability in therange from about 0.1 cc/cm²/s (cubic centimeter per centimeter squareper second) to about 20 cc/cm²/s when measured at 125 Pascal (Pa)pressure. This includes from about 0.01 cc/cm²/s to about 20 cc/cm²/s,about 0.1 cc/cm²/s to about 15 cc/cm²/s, about 0.5 cc/cm²/s to about 10cc/cm²/s, about 0.5 cc/cm²/s to about 8 cc/cm²/s, about 0.5 cc/cm²/s toabout 6 cc/cm²/s, about 0.5 cc/cm²/s to about 4 cc/cm²/s, or about 0.5cc/cm²/s to about 3 cc/cm²/s, at 125 Pa, and ranges between any two ofthese values or less than any one of these values. In some embodiments,the separator has air permeability of from about 0.5 cc/cm²/s to about 4cc/cm²/s, at 125 Pa. In some embodiments, the separator has airpermeability of from about 0.5 cc/cm²/s to about 3.8 cc/cm²/s, at 125Pa.

In various embodiments, the separator may have air permeability in therange from about 50 cc/cm²/min (cubic centimeter per centimeter squareper minute) to about 30,000 cc/cm²/s when measured at 1 Kilopascal (KPa)pressure. This includes air permeability of from about 100 cc/cm²/min toabout 10,000 cc/cm²/min, about 200 cc/cm²/min to about 8000 cc/cm²/min,about 300 cc/cm²/min to about 5000 cc/cm²/min, about 500 cc/cm²/min toabout 3000 cc/cm²/min, about 600 cc/cm²/min to about 2500 cc/cm²/min,about 700 cc/cm²/min to about 2000 cc/cm²/min, or about 800 cc/cm²/minto about 1000 cc/cm²/min, at 1 KPa, and ranges between any two of thesevalues or less than any one of these values. In some embodiments, theseparator has an air permeability of from about 500 cc/cm²/min to about3000 cc/cm²/min, at 1 KPa. In some embodiments, the separator has an airpermeability of from about 240 cc/cm²/min to about 1824 cc/cm²/min, at 1KPa.

In various embodiments, the separator may have a desired basis weightranging from about 1 g/m²to about 100 g/m². This includes a desiredbasis weight of from about 1 g/m² to about 90 g/m², about 1 g/m²to about80 g/m², about 5 g/m²to about 70 g/m², about 10 g/m²to about 50 g/m²,about 20 g/m² to about 32 g/m², about 22 g/m² to about 30 g/m², or about23 g/m² to about 28 g/m²,and ranges between any two of these values orless than any one of these values. In some embodiments, the separatorhas a desired basis weight of from about 20 g/m²to about 32 g/m². Inother embodiments, the separator has a desired basis weight of fromabout 24 g/m²to about 30 g/m².

Superior high rate performance is provided by an electrochemical cellwhen there is a rapid, preferential transport of the electrolyte throughthe separator. Accordingly, the separator is designed to be thin aspossible, in order to maximize the rate of discharge. In variousembodiments, the separator may have a dry thickness ranging from about10 microns to about 200 microns. This includes a dry thickness of fromabout 20 microns to about 150 microns, about 40 microns to about 175microns, about 60 micron to about 120 microns, about 70 microns to about100 microns, about 75 microns to about 95 microns, or about 80 micronsto about 90 microns, and ranges between any two of these values or lessthan any one of these values. In some embodiments, the separator has adry thickness of from about 60 microns to about 120 microns. In otherembodiments, the separator has a dry thickness of from about 75 micronsto about 95 microns.

In one aspect, provided is a separator, and/or an electrochemical cellcomprising such a separator, which includes a non-conductive, porousmaterial having a maximum pore size of about 19 microns. In one aspect,provided is a separator, and/or an electrochemical cell comprising sucha separator, which includes a non-conductive, porous material having amean pore size of about 1 micron to about 6 microns. In another aspect,provided is a separator, and/or an electrochemical cell comprising sucha separator, which includes a non-conductive, porous material having anair permeability of about 0.5 cc/cm²/s to about 3.8 cc/cm²/s at 125 Pa.In yet another aspect, provided is a separator, and/or anelectrochemical cell comprising such a separator, which includes anon-conductive, porous material having an air permeability of from about500 cc/cm²/min to about 3000 cc/cm²/min, at 1KPa. In another aspect,provided is a separator, and/or an electrochemical cell comprising sucha separator, which includes a non-conductive, porous material having abasis weight of about 20 g/m² to about 32 g/m². In yet another aspect,provided is a separator, and/or an electrochemical cell comprising sucha separator, which includes a non-conductive, porous material having adry thickness of from about 60 microns to about 120 microns. Each ofthese aspects is combinable with the other aspects and embodiments.

In various embodiments, the separator described herein is referred to as“Paper 1.” Generally, the number of wraps of the separator material usedin the electrochemical cell may be optimized for a given applicationand/or to achieve a desired performance within the cell. The separatordisclosed herein allows the use of less than 3 wraps of the paper. Insome embodiments, the Paper 1 separator may be designed to include asingle layer of the non-conductive, porous material sheet wound twice.In various embodiments, the separator includes greater than about 1 andless than about 4, greater than about 1.1 and less than about 3, greaterthan about 1.2 and less than about 2, or greater than about 1.3 and lessthan about 1.8 (wherein a wrap number of greater than 1 indicates somedegree of overlap of the separator is present within the cell). In someembodiments, the separator includes less than about 2 wraps of thenon-conductive, porous material. In some embodiments, the separatorincludes less than about 3 wraps of the non-conductive, porous material.In other embodiments, the number of wraps is greater than about 3 bandless than about 4. It should be noted that the number of “wraps” for awound separator configuration indicates the number of windings of theseparator, which may itself be multi-layer or single layer. For example,a 1×2 wrap indicates that the separator has 2 wraps of a single layerseparator. In some embodiments, the separator may be designed to includea single layer of the non-conductive, porous material sheet wound twice.

The separator described herein has several advantages with regard topore size to prevent short-circuiting resulting from the transport ofactive materials, improved mechanical strength and electrolytepermeability, low electrical resistance, sufficient pliability, highchemical resistance, and high thermal stability. Without being held toany particular theory, it is generally believed that the separatordisclosed herein is advantageous because it occupies or consumes lessvolume, as compared to a conventional separator, thus decreasing thetotal separator dry thickness and making space for added amount ofactive ingredients such as that of anode or cathode electrodes.

Further, the separator acts to improve shorting resistance, given that abarrier with small pore size provides internal shorting resistance thatwould not be possible with the conventional separators not having thecharacteristics described herein.

The performance of the electrochemical cell including the separator ofthe present technology can be further enhanced with the use of improvedzinc anode material, relative to that of cells made with conventionalzinc anode material. Accordingly, in various embodiments, the separatorof the present technology is used in conjunction with the anode whichincludes high fines (HF) anode active materials, where the fines contentis higher and the coarse content is lower than that of conventionalstandard zinc powders. In various embodiments, the anode active materialmay have a particle size distribution of less than about 15 wt % dust,about 10 wt % to about 70 wt % fines and about 5 wt % to about 35 wt %coarse particles. In some embodiments, the anode active material of thepresent technology has a particle size distribution of less than about10 wt % dust, about 15 wt % to about 65 wt % fines and about 5 wt % toabout 25 wt % coarse particles. A suitable zinc particle sizedistribution may be one in which about 25% to about 45% by weight of theanode active material, relative to the total amount of anode activematerial has a particle size of less than about 75 microns, about 5% toabout 25% by weight relative of the total zinc alloy has a particle sizeof greater than about 150 micrometers, about less than 2% by weight ofthe total zinc alloy has a particle size greater than 425 microns, andless than 10% by weight of the anode active material, relative to thetotal amount of anode active material has a particle size of less thanabout 45 microns.

In some embodiments, the type of the anode active material used, havingan optimized particle size distribution and apparent density, may besimilar to that described in substantial detail in U.S. PatentPublication No. 2015/0037627, the complete disclosure of which isincorporated herein by reference. In other embodiments, the anode activematerial has an apparent density of from about 2.00 g/cc to about 4.15g/cc, in some embodiments from about 2.25 g/cc to about 3.85 g/cc, insome embodiments about 2.50 g/cc to about 3.50 g/cc, in some embodimentsabout 2.60 g/cc to about 3.35 g/cc, and in some embodiments about 2.70g/cc to about 3.15 g/cc.

Although the embodiments described herein generally relate to alkalinecells, they are applicable to other suitable electrochemical cellsincluding, for example, alkaline cylindrical cells, e.g., metal-metaloxide cell, as well as galvanic cells, such as in metal-air cells, e.g.,zinc-air cell. Among the cylindrical metal-metal oxide cells andmetal-air cells, the anode material is applicable to those shaped forAA, AAA, AAAA, C, or D cells. These include, for example, alkaline cellsLR03, LR6, LR8D425, LR14, LR20. The electrochemical cells haveapplications to non-cylindrical cells, such as flat cells (e.g.,prismatic cells and button cells) and rounded flat cells (e.g., having aracetrack cross-section). Metal-air cells which include the anodedescribed herein may usefully be constructed as button cells for thevarious applications such as hearing aid batteries, and in watches,clocks, timers, calculators, laser pointers, toys, and other novelties.Suitable electrochemical cells may also include any metal air cell usingflat, bent, or cylindrical electrodes. Use of the anode as a componentin other forms of electrochemical cells is also contemplated.

The anode of the electrochemical cell may be a gelled anode whichincludes, an anode active material, an alkaline electrolyte, a gellingagent, and optionally one or more surfactants as corrosion inhibitors.The gelled anode may include also other components or additives such as,for example, absorbents, inorganic gassing inhibitors, and additives tocontrol electrical short circuit between the anode and cathodeelectrodes. The anode active material may include a zinc alloy whichincludes from about 20 ppm to about 750 ppm of one or more alloyingelement selected from, bismuth, indium, lead, and aluminum. In someembodiments, the zinc alloy includes bismuth and indium as main alloyingelements, each at a concentration of about 150 ppm, 200 ppm, or 250 ppm.The anode includes high fines (HF) anode active materials, as describedhereinabove, where the fines content is higher and coarse content islower than that of conventional standard zinc powders.

The gelled anode may include an alkaline electrolyte, and in someembodiments an alkaline electrolyte having a relatively low hydroxidecontent. Suitable alkaline electrolytes include, for example, aqueoussolutions of potassium hydroxide, sodium hydroxide, lithium hydroxide,as well as combinations of any two or more thereof. In one particularembodiment, however, a potassium hydroxide-containing electrolyte isused. In other embodiments, the alkaline electrolyte includes water andpotassium hydroxide.

The electrolytes advantageously have a lower concentration of hydroxideions in the electrolyte than those used in conventional cells. Forexample, the electrolyte may have a hydroxide (e.g., potassiumhydroxide) concentration of less than about 36%, based on the totalelectrolyte weight. This includes a hydroxide concentration of less thanabout 35%, less than about 34%, less than about 32%, less than about30%, less than about 29%, or less than about 28%, based on the totalelectrolyte weight. In various embodiments, the electrolyte has ahydroxide concentration of about 25% to about 34%, about 26% to about34%, about 27% to about 34%, about 28% to about 34%, or about 28% toabout 32%, and ranges between any two of these values or less than anyone of these values. This includes a hydroxide concentration of about35%, about 34%, about 32%, about 31%, about 30.5%, about 30%, about 29%,or about 28%, based on the total electrolyte weight. In an illustrativeembodiment, the hydroxide concentration of the electrolyte is about 27%to about 31% by weight, based on the total weight of the electrolyte.

The anode may be prepared by formulating an electrolyte, preparing acoated metal anode, which includes the gelling agent, and then combiningthe electrolyte and the coated metal anode to form a gelled anode. Thegelling agent of the present disclosure may include, for example, ahighly cross-linked, polymeric chemical compound that has negativelycharged acid groups, such as a polyacrylic acid gelling agent having ahigh degree of crosslinking.). Highly crosslinked polyacrylic acidgelling agents, are commercially available under the names Carbopol®(Carbopol® 940, Carbopol® 934, or Carbopol® 674) from LubrizolCorporation (Wickliffe, Ohio), Flogel® (e.g., Flogel® 700 or Flogel®800) from SNF Holding Company (Riceboro, Ga.), and Polygel® (e.g.,Polygel® CK, or Polygel® CA) from 3V Sigma S.P.A. (Georgetown, S.C.),among others, are suitable for use in accordance with the presentdisclosure. The concentration of the gelling agent in the gelled anodemay be from about 0.20 wt % to about 1.5 wt % , about 0.40 wt % to about1.00 wt %, about 0.60 wt % to about 0.70 wt % , or about 0.625 wt % toabout 0.675 wt % , relative to the total weight of the gelled anode.

The cathode of the electrochemical cell may include any cathode activematerial generally recognized in the art for use in alkalineelectrochemical cells. The cathode active material may be amorphous orcrystalline, or a mixture of amorphous and crystalline. For example, thecathode active material may include, or be selected from, an oxide ofcopper, an oxide of manganese as electrolytic, chemical, or natural type(e.g., EMD, CMD, NMD, or a mixture of any two or more thereof), an oxideof silver, and/or an oxide or hydroxide of nickel, as well as a mixtureof two or more of these oxides or hydroxide. Suitable examples ofpositive electrode materials include, but are not limited to, MnO₂ (EMD,CMD, NMD, and mixtures thereof), NiO, NiOOH, Cu(OH)₂, cobalt oxide,PbO₂, AgO, Ag₂O, Ag₂Cu₂O₃, CuAgO₂, CuMnO₂, Cu Mn₂O₄, Cu₂MnO₄,Cu_(3-x)Mn_(x)O₃, Cu_(1-x)Mn_(x)O₂, Cu_(2-x)Mn_(x)O₂ (where x<2),Cu_(3-x)Mn_(x)P₄ (where x<3), Cu₂Ag₂O₄, or a combination of any two ormore thereof.

An exemplary embodiment of an alkaline electrochemical cell is describedin PCT Publication No. WO 2016/183373, the complete disclosure of whichis incorporated herein by reference.

As further detailed elsewhere herein, the electrochemical cells of thepresent disclosure have been observed to exhibit improved performancecharacteristics, which may be measured or tested in accordance withseveral methods under the American National Standards Institute (ANSI).Results of various tests of cells of the present disclosure are detailedbelow in the Examples.

The following Examples describe various embodiments of the presentdisclosure. Other embodiments within the scope of the appended claimswill be apparent to one of ordinary skill in the art considering thespecification or practice of the disclosure provided herein. It istherefore intended that the specification, together with the Examples,be considered exemplary only, with the scope and spirit of thedisclosure being indicated by the claims, which follow the Examples.

EXAMPLES

In the Examples presented below, electrochemical cells including theseparators of the present technology were tested for DSC performance,partial discharge cell gassing, undischarged cell gassing, andconditions after storage.

General. Characterization. Air permeability of the separators wasdetermined by using a PMI Capillary Flow Porometer and is reported incc/cm²/s or cc/cm²/min. Basis Weight of the separators was determined byISO 536 (2012), which is hereby incorporated by reference and isreported in g/m². Dry thickness of the separators was determined by witha Mitutoyo Absolute Gauge using a flat probe of 10 mm diameter with lowmeasuring force, and is reported in microns. Pore size was determined byPMI Capillary Flow Porometer and is reported in microns.

Example 1. Preparation of LR6 cells. Control cells having a conventional1×3 separator were prepared. The conventional separator has a mean poresize of 9 micron, a maximum pore size of 32 microns as measured with aPMI capillary flow porometer, an air permeability of 22.1 cc/cm²/s at125 Pa, a basis weight of 23 g/m² and a dry thickness of 80 microns.

Cells were also prepared using a 1×2 wrap of a non-woven paper (Paper 1)having a mean pore size of 1-6 microns as measured with a PMI capillaryflow porometer, an air permeability of 1-4 cc/cm²/s at 125 Pa, a desiredbasis weight of 20-32 g/m² and a dry thickness of 60-120 microns.

Example 2. Electrochemical cells may be tested in accordance withmethods under the American National Standards Institute (ANSI). Forexample, the ANSI data plotted in the figures correspond to testing doneaccording to ANSI C18.1M, Part 2-2011, which is hereby incorporated byreference. These tests include determining cell performance/longevityunder various discharge modes including cell pulse discharge,intermittent cell discharge, high temperature (HT) storage performanceor Digital Still Camera (DSC), among other tests. Tests also includedetermining cell performance/longevity by discharging them in variousdevices such as portable lighting, CD-games, digital audio, andremote-radio-clock, toys, and Heavy Industrial Flashlight (HIFT). Theresults of various tests of cells of the present disclosure are detailedbelow.

FIG. 1 shows the average ANSI discharge performance of LR6 alkalinecells made with conventional zinc anode (without higher level of fines)and conventional separator at a zinc loading of 68%. It was observedthat the average ANSI of seven tests for the Paper 1 separator of thepresent technology is improved by about 2.3% compared to theconventional separator. The most improved test was personal grooming(750 mA, 2 minute (min)/hour (hr), 8 hr/day), which improved by about18.2%, as seen in FIG. 2. Further, the Toy test (3.9 ohms (Ω), 1hr/day), was improved by 0.7%. No statistical performance impact wasobserved among the other tests including DSC (digital still camera, 1500mW 2 seconds (s), 650 mW 28 s 5, min/hr), portable lighting (3.9 n, 4min/hr, 8 hr/day), CD-games (250 mA, 1 hr/day), digital audio (100 mA, 1hr/day), and remote-radio-clock (50 mA, 1 hr/12 hr, 24 hr) tests.

The performance gains with a separator of 1×2 Paper 1 was confirmedafter storing the cells at high temperature (HT). FIG. 3 shows the LR6average HT performance of toy test after 1-week storage at 71° C. (160°F.), (1 HT), and of Game and DSC tests both after 2-weeks of storage at54.4° C. (130° F.) (½HT). It is seen from FIG. 3 that cells made with1×2 Paper 1 exhibit a net gain of 7% over conventional cells made with1×3 standard separator paper. The main gain after HT storage was in theDSC test, amounting to 17%, as shown in FIG. 4. The dischargeperformance gains with the 1×2 separator arrangement can be maximized byincreasing the zinc loading above 68%.

FIG. 5 displays the no-delay ANSI average performance of LR6 cells madewith 1×2Paper 1 with pre-wet (PW) levels of KOH solution at 1.45 gram(g), 1.50 g, and 1.55 g, relative to the data of reference cells madewith conventional 1×3 separator paper. The cells used HF zinc at 70%zinc loading. The average ANSI of cells made with HF zinc and 1×2 Paper1 wrapping improved by 2% to 4% relative to the cell made with HF zincand conventional 1×3 wrapping separator.

The DSC performance after one month storage (1RT) improved from 3% to 8%and personal grooming improved from 11% to 15%, relative to the cellmade with HF zinc and conventional 1×3 paper wrapping separator,depending on the amount of pre-wet electrolyte, as shown in FIG. 6 andFIG. 7, respectively. The corresponding HT performance for LR6 cellsmade with HF zinc at 70% is illustrated in FIG. 8. The average gainsranging from 2.1% to 8.6% correspond to DSC and Toy tests after 1 HTstorage and to Game and DSC tests after ½ HT storage.

While certain embodiments have been illustrated and described, it shouldbe understood that changes and modifications can be made therein inaccordance with ordinary skill in the art without departing from thetechnology in its broader aspects as defined in the following claims.

The embodiments, illustratively described herein may suitably bepracticed in the absence of any element or elements, limitation orlimitations, not specifically disclosed herein. Thus, for example, theterms “comprising,” “including,” “containing,” etc. shall be readexpansively and without limitation. Additionally, the terms andexpressions employed herein have been used as terms of description andnot of limitation, and there is no intention in the use of such termsand expressions of excluding any equivalents of the features shown anddescribed or portions thereof, but it is recognized that variousmodifications are possible within the scope of the claimed technology.Additionally, the phrase “consisting essentially of” will be understoodto include those elements specifically recited and those additionalelements that do not materially affect the basic and novelcharacteristics of the claimed technology. The phrase “consisting of”excludes any element not specified.

The present disclosure is not to be limited in terms of the particularembodiments described in this application. Many modifications andvariations can be made without departing from its spirit and scope, aswill be apparent to those skilled in the art. Functionally equivalentmethods and compositions within the scope of the disclosure, in additionto those enumerated herein, will be apparent to those skilled in the artfrom the foregoing descriptions. Such modifications and variations areintended to fall within the scope of the appended claims. The presentdisclosure is to be limited only by the terms of the appended claims,along with the full scope of equivalents to which such claims areentitled. It is to be understood that this disclosure is not limited toparticular methods, reagents, compounds compositions or biologicalsystems, which can of course vary. It is also to be understood that theterminology used herein is for the purpose of describing particularembodiments only, and is not intended to be limiting.

As will be understood by one skilled in the art, for any and allpurposes, particularly in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” “greater than,” “less than,” and the like,include the number recited and refer to ranges which can be subsequentlybroken down into subranges as discussed above. Finally, as will beunderstood by one skilled in the art, a range includes each individualmember.

All publications, patent applications, issued patents, and otherdocuments referred to in this specification are herein incorporated byreference as if each individual publication, patent application, issuedpatent, or other document was specifically and individually indicated tobe incorporated by reference in its entirety. Definitions that arecontained in text incorporated by reference are excluded to the extentthat they contradict definitions in this disclosure.

The present technology may include, but is not limited to, the featuresand combinations of features recited in the following letteredparagraphs, it being understood that the following paragraphs should notbe interpreted as limiting the scope of the claims as appended hereto ormandating that all such features must necessarily be included in suchclaims:

-   A. An alkaline electrochemical cell comprising:

a cathode;

a gelled anode comprising an anode active material and an electrolyte;and

a separator disposed between the cathode and the anode;

-   -   wherein the separator comprises a non-conductive, porous        material having a mean pore size of about 1 micron to about 5        microns, a maximum pore size of about 19 microns, and an air        permeability of about 0.5 cc/cm²/s to about 3.8 cc/cm²/s at 125        Pa.

-   B. The alkaline electrochemical cell of Paragraph A, wherein the    non-conductive, porous material is non-woven.

-   C. The alkaline electrochemical cell of Paragraph A or Paragraph B,    wherein the non-conductive, porous material comprises polyvinyl    alcohol.

-   D. The alkaline electrochemical cell of any one of Paragraphs A-C,    wherein the separator has an air permeability of about 500    cc/cm²/min to about 3000 cc/cm²/min, at 1 KPa.

-   E. The alkaline electrochemical cell of any one of Paragraphs A-D,    wherein the separator has a basis weight of about 20 g/m² to about    32 g/m².

-   F. The alkaline electrochemical cell of any one of Paragraphs A-E,    wherein the separator has a dry thickness of about 60 microns to    about 120 microns.

-   G. The alkaline electrochemical cell of any one of Paragraphs A-F,    wherein the separator comprises less than 3 full wraps of the    non-conductive, porous material.

-   H. The alkaline electrochemical cell of any one of Paragraphs A-G,    wherein the anode active material comprises a zinc alloy.

-   I. The alkaline electrochemical cell of Paragraph H, wherein the    zinc alloy comprises from about 130 ppm to about 270 ppm of bismuth    and about 130 ppm to about 270 ppm of indium.

-   J. The alkaline electrochemical cell of any one of Paragraphs A-I,    wherein about 20% to about 45% by weight of the anode active    material relative to the total amount of anode active material has a    particle size of less than about 75 microns, about 8% to about 25%    by weight relative of the total zinc alloy has a particle size of    greater than about 150 micrometers, and less than 10% by weight of    the anode active material relative to the total amount of anode    active material has a particle size of less than about 45 microns.

-   K. The alkaline electrochemical cell of any one of Paragraphs A-J,    wherein the anode active material has an apparent density from about    2.50 g/cc to about 3.30 g/cc.

-   L. The alkaline electrochemical cell of any one of Paragraphs A-K,    wherein the electrolyte has a hydroxide concentration of about 24 wt    % to about 37 wt %.

-   M. An alkaline electrochemical cell separator comprising a    non-conductive, porous material, wherein the separator has a mean    pore size of about 1 micron to about 5 microns, a maximum pore size    of about 19 microns, and an air permeability of about 0.5 cc/cm²/s    to about 3.8 cc/cm²/s at 125 Pa.

-   N. The alkaline electrochemical cell separator of Paragraph M,    wherein the non-conductive, porous material is non-woven.

-   O. The alkaline electrochemical cell separator of Paragraph M or    Paragraph N, wherein the non-conductive, porous material comprises    polyvinyl alcohol.

-   P. The alkaline electrochemical cell separator of any one of    Paragraphs M-O, wherein the separator has an air permeability of    from about 500 cc/cm²/min to about 3000 cc/cm²/min, at 1 KPa.

-   Q. The alkaline electrochemical cell separator of any one of    Paragraphs M-P, wherein the separator has a basis weight of about 20    g/m² to about 32 g/m².

-   R. The alkaline electrochemical cell separator of any one of    Paragraphs M-Q, wherein the separator has a dry thickness of from    about 60 microns to about 120 microns.

-   S. The alkaline electrochemical cell separator of any one of    Paragraphs M-R, wherein the separator is permeable to hydroxide ions    and water.

Other embodiments are set forth in the following claims.

1.-19. (canceled)
 20. An alkaline electrochemical cell comprising: anair cathode; an anode comprising an anode active material and anelectrolyte; and a separator disposed between the air cathode and theanode; wherein: the separator comprises a non-conductive, porousmaterial having a mean pore size of about 1 micron to about 5 microns, amaximum pore size of about 19 microns, and an air permeability of about0.5 cc/cm²/s to about 3.8 cc/cm²/s at 125 Pa; and the alkalineelectrochemical cell is a metal-air cell.
 21. The alkalineelectrochemical cell of claim 20, wherein the non-conductive, porousmaterial comprises polyvinyl alcohol.
 22. The alkaline electrochemicalcell of claim 20, wherein the non-conductive, porous material isnon-woven.
 23. The alkaline electrochemical cell of claim 22, whereinthe non-conductive, porous material comprises polyvinyl alcohol.
 24. Thealkaline electrochemical cell of claim 20, wherein the separator has anair permeability of about 500 cc/cm²/min to about 3000 cc/cm²/min, at 1KPa.
 25. The alkaline electrochemical cell of claim 20, wherein theseparator has a basis weight of about 20 g/m² to about 32 g/m².
 26. Thealkaline electrochemical cell of claim 20, wherein the separator has adry thickness of about 60 microns to about 120 microns.
 27. The alkalineelectrochemical cell of claim 20, wherein the separator comprises lessthan 3 full layers of the non-conductive, porous material.
 28. Thealkaline electrochemical cell of claim 20, wherein the separatorcomprises less than 4 full layers of the non-conductive, porousmaterial.
 29. The alkaline electrochemical cell of claim 20, whereinabout 20% to about 45% by weight of the anode active material relativeto the total amount of anode active material has a particle size of lessthan about 75 microns, about 8% to about 25% by weight relative of thetotal zinc alloy has a particle size of greater than about 150micrometers, and less than 10% by weight of the anode active materialrelative to the total amount of anode active material has a particlesize of less than about 45 microns.
 30. The alkaline electrochemicalcell of claim 20, wherein the anode active material has an apparentdensity from about 2.50 g/cc to about 3.30 g/cc.
 31. The alkalineelectrochemical cell of claim 20, wherein the electrolyte has ahydroxide concentration of about 24 wt % to about 37 wt %.
 32. Thealkaline electrochemical cell of claim 20, wherein the anode activematerial comprises a zinc alloy.
 33. The alkaline electrochemical cellof claim 32, wherein the zinc alloy comprises lead, indium, andaluminum.
 34. The alkaline electrochemical cell of claim 32, wherein thezinc alloy comprises from about 50 ppm to about 500 ppm of lead, fromabout 100 ppm to about 300 ppm of indium, and from about 20 to 750 ppmaluminum.
 35. The alkaline electrochemical cell of claim 32, wherein thezinc alloy comprises from about 130 ppm to about 270 ppm of bismuth andabout 130 ppm to about 270 ppm of indium.
 36. The alkalineelectrochemical cell of claim 20, wherein the anode further comprises agellant.